Will Warzone and Fortnite be playable without Live GOLD

Just for reference, PlayStation & Nintendo Switch both have paid online, meaning you have to pay to have online access and privileges. PlayStation has been this way since the release of the PS4 and Switch has had paid online since the release of the Switch.
Xbox Live Gold is no different than those two aside from Switch being the cheapest (But also on weaker hardware and a relatively mediocre online experience).

If you wanna play these games without having to play online, your best option would just to play them on PC, the only downside being you need a decent gaming rig to even play said games. Which said rigs can cost a good chunk of money, cheapest being built,
but that requires knowledge on how to build a PC. You can obviously buy pre-built PCs, but just a decent one can reach around $1000 depending on where and who you're buying from.

Just for reference, PlayStation & Nintendo Switch both have paid online, meaning you have to pay to have online access and privileges. PlayStation has been this way since the release of the PS4 and Switch has had paid online since the release of
the Switch. Xbox Live Gold is no different than those two aside from Switch being the cheapest (But also on weaker hardware and a relatively mediocre online experience).

If you wanna play these games without having to play online, your best option would just to play them on PC, the only downside being you need a decent gaming rig to even play said games. Which said rigs can cost a good chunk of money, cheapest being built,
but that requires knowledge on how to build a PC. You can obviously buy pre-built PCs, but just a decent one can reach around $1000 depending on where and who you're buying from.

just for reference for your self, playstation and switch do NOT require a paid subscription to play FREE TO PLAY games only xbox does. (none of the xbox live money goes to the devs that actually RUN the online servers for third party games, it only pays
for the xbox fist party games servers and the user servers)

Also my sons gaming PC gets over 120FPS in warzone at high settings (which is higher than xbox one x) and his pc cost £450 which i built and building pc's is super super easy and can be fun.

To the OP, i'm afraid that all online game features are locked behind the paywall on xbox and look to be staying that way until Microsoft announce any changes they may do.

check on https://account.microsoft.com/ if your gold Subscription is active..without it you cannot play fortnite neither cod warzone.

Free-to-play games will be playable without Gold, but Gold will still be required for non-free games. So Fortnite you can play without Gold. Call of Duty would need Gold.

Fortnite is a free-to-play game which means it does not require an Xbox Live Gold subscription.

Xbox Live Gold subscription is not just required for free-to-play games such as Fortnite, Apex Legends, Warzone 2.0 etc.